Clinical utility of HBV surface antigen quantification in HBV e antigen-negative chronic HBV infection

Chronic hepatitis B virus (HBV) infection is a serious problem owing to its worldwide distribution and potential adverse sequelae that include cirrhosis and/or hepatocellular carcinoma. Current antiviral therapies have much improved outcomes, but few patients achieve the ultimate goal of hepatitis B surface antigen (HBsAg) loss (functional cure). As hepatitis B e antigen (HBeAg)-negative chronic HBV infection is the final phase prior to HBsAg loss, the management of patients in this phase together with quantification of HBsAg has attracted increasing clinical and research interest. This Review integrates the findings from research in HBsAg kinetics and discusses how they might inform our understanding and management of HBeAg-negative chronic HBV infection. Studies have shown that HBsAg levels are highly predictive of the presence of inactive HBV infection and that serial changes in HBsAg levels might predict HBsAg loss within 1-3 years. Data also suggest that quantitative HBsAg monitoring is important during hepatitis flare and antiviral therapy, especially in the timing of the decision to stop therapy and to start off-therapy retreatment. These findings have shed new light on the natural course of HBV infection and might lead to optimization of the management of HBeAg-negative chronic HBV infection and contribute to the paradigm shift from indefinite to finite therapy for patients with HBV infection.